tarring days. this week 40 state also see temperatures of 90 or more. >> looks like we'll be dealing with this high pressure system for many days to come as it intensifies. >> reporter: for beach goers, it means fun in the sum. >> coming our early before it gets packed with people. >> reporter: for some people, this extreme heat can be extremely dangerous. >> they'll complain of dizziness, weakness, being light owedded. they may exib signs of confusion. >> reporter: experts say drink plenty of water, stay out of the sun and avoid strene knewous activity. not everyone is heeding the warning. these hard cor athletes in racine, wisconsin, participated in an iron man triathlon.